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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Prospectively registered

Titles & IDs
Public title
Effects of protein on gut hormones and motility, and appetite and energy intake in undernourished compared with healthy older individuals
Scientific title
Effects of intraduodenal protein, on energy intake, appetite, antropyloroduodenal motility, amino acids, hormones and glucose in undernourished compared with healthy older individuals
Secondary ID [1] 281086 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Malnutrition in older people 287239 0
Condition category
Condition code
Diet and Nutrition 287563 287563 0 0
Other diet and nutrition disorders
Oral and Gastrointestinal 287564 287564 0 0
Normal oral and gastrointestinal development and function

Study type
Description of intervention(s) / exposure
A single 60 minute intraduodenal infusion at 4mL/min of
i) 0 kcal/min (saline control)
ii) 1.5 kcal/min (Whey Protein Hydrolysate)
in 12 undernourished and 12 'healthy' older subjects

Appetite sensation questionnaires in the form of a Visual Analogue Scale (VAS), blood samples.

A standard buffet meal will be provided at the end of the 60 minute infusion from which the volunteer has 30 minutes to eat until comfortably full. The buffet meal consists of 300ml orange juice, 600ml water, 375ml iced coffee, 4 slices white bread, 4 slices brown bread, 100g deli leg ham, 100g virginian chicken, 4 slices cheese, 100g tomato, 100g cucumber, 100g lettuce, 2 portions mayonnaise, 2 portions margarine, 1 medium apple, 1 medium banana, 200g chocolate custard, 150g fruit salad, 200g strawberry yoghurt, and a 14g milky way bar.

Each volunteer will receive one of each infusion solution over 2 study days. Study visits will be seperated by no less than 3 days.

Each study visit will last approximately 3-6 hours.
Intervention code [1] 285538 0
Treatment: Other
Intervention code [2] 285553 0
Comparator / control treatment
Volunteers will act as their own control via administration of a single 0kcal/min intraduodenal infusion of saline solution, delivered at a rate of 4mL/min for 60 minutes, to enable comparison to nutrient containing infusion.

Undernourished older people will be compared to 'healthy' older people.
Control group

Primary outcome [1] 287816 0
Antropyloroduodenal motility (antropyloroduodenal pressures; number of antral, duodenal and isolated pyloric pressure waves; basal pyloric pressure) assessed by Manometry.
Timepoint [1] 287816 0
Intubation occurs on subject arrival.

At t= -15 until 0, a baseline of the antropyloroduodenal (APD) motility is recorded.

Infusion starts at t=0 until t=60 minutes. APD motility is assessed continuously for the duration of the infusion (t=0-60 minutes).

Subject is extubated at t=60 minutes.
Primary outcome [2] 287817 0
Plasma concentrations of gut hormones (cholecyctokinin (CKK), glucagon-like peptide-1 (GLP-1), peptide YY (PYY), gastric inhibitory polypeptide (GIP), ghrelin, glucagon and insulin), glucose and amino acids.
Timepoint [2] 287817 0
Blood samples are taken at t= 0, 15, 30, 45 and 60 minutes.
Primary outcome [3] 287818 0
Macronutrient and total energy intake of standard buffet meal are determined using Foodworks Software.
Timepoint [3] 287818 0
Buffet meal will be presented at the end of the infusion and after extubation (t=60). The subject will be allowed to freely consume food for 30 minutes until comfortably full (until t=90).
Secondary outcome [1] 298878 0
Appetite sensations using a Visual Analogue Scale (VAS) (nausea, hunger, fullness, desire to eat, thirst).
Timepoint [1] 298878 0
VAS questionnaires are given at t= 0, 15, 30, 45, 60 and 90 minutes.
Secondary outcome [2] 298879 0
Blood pressure and heart rate are determined using an automatic sphygmomanometer.
Timepoint [2] 298879 0
Blood pressure and heart rate are measured at t= 0, 15, 30, 45, 60 and 90 minutes.

Key inclusion criteria
Undernourished older people:

at risk of malnourishment + malnourishment defined by a well validated, widely used, screening tool that is associated with poor outcomes in older people: the Mini Nutritional Assessment (MNA) with a score <24 out of 30

and, at least one of: self-reported weight loss in the previous 3 months, or a Body Mass Index (BMI) <22 kg/m2

'Healthy' older people:

BMI: 20-30 kg/m2

Weight stable (<5% fluctuation in body weight in previous 3 months).
Minimum age
65 Years
Maximum age
No limit
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
Significant gastrointestinal symptoms, disease, or surgery.

Current gallbladder or pancreatic disease; diabetes mellitus; epilepsy; cardiovasculr or respiratory diseases; any other illnesses as assessed by the investigator (including chronic illnesses not explicitly listed above).

Impaired cognitive function.


Use of prescribed or non-prescribed medications (including vitamins and herbal supplements) which may effect gastrointestinal function or appetite.

Lactose intolerant or other food allergies; intolerance or allergy to paracetomol.

Individuals with low ferritin levels or who have donated blood in the 12 weeks prior to taking part in the study.

Current intake of >2 standard drinks on >5 days per week.

Current smokers of cigarettes/cigars/marijuana.

Current intake of any illicit substance.

Experience claustrophobia in confined spaces.

Unable to tolerate nasogastrointestinal tube, or to comprehend study protocol.

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Volunteers are asked to visit the clinic for a screening visit. A series of screening questionnaires are answered by the volunteer, and a blood sample is taken for determination of ferritin levels. Eligibility is determined based on the inclusion/exclusion criteria. A signed informed consent form is obtained and study dates are established. Eligible volunteers are assigned a subject number and randomised into a treatment for each study visit using a randomisation table created on an excel spreadsheet. Randomisation involves contacting the holder of the randomisation table (study assistant) to inform them of the subjects details and study dates. The unblinded study assistant is therefore responsible for allocating a random treatment to the subject and preparing the solution for infusion on each study day.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
The randomisation table was created using Microsoft Office Excel.
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?

Intervention assignment
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis

Recruitment status
Reason for early stopping/withdrawal
Lack of funding/staff/facilities
Participant recruitment difficulties
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment in Australia
Recruitment state(s)

Funding & Sponsors
Funding source category [1] 285871 0
Government body
Name [1] 285871 0
National Health and Medical Research Council Grant
Address [1] 285871 0
Level 1 16 Marcus Clarke Street
Canberra ACT 2601
Country [1] 285871 0
Primary sponsor type
Dr Stijn Soenen
Level 6 Eleanor Harrald Building,
Frome Road,
Adelaide, SA 5000
Secondary sponsor category [1] 284695 0
Name [1] 284695 0
University of Adelaide
Address [1] 284695 0
North Terrace
Adelaide, SA 5005
Country [1] 284695 0
Secondary sponsor category [2] 284696 0
Name [2] 284696 0
Royal Adelaide Hospital
Address [2] 284696 0
North Terrace
Adelaide, SA 5005
Country [2] 284696 0

Ethics approval
Ethics application status
Ethics committee name [1] 287899 0
Royal Adelaide Hospital Research Ethics Committee
Ethics committee address [1] 287899 0
Level 3, Hanson Institute, North Terrace
Adelaide, South Australia, 5000
Ethics committee country [1] 287899 0
Date submitted for ethics approval [1] 287899 0
Approval date [1] 287899 0
Ethics approval number [1] 287899 0

Brief summary
Ageing is associated with a physiological reduction of appetite and energy intake, which has been called the “anorexia of ageing”. Dietary supplementation with liquid protein preparations is now used frequently to increase energy and protein intake in older adults in both institutionalized and community-dwelling populations. Although the latter would appear a logical approach, evidence for success of increased energy intake in older individuals is limited. There is consensus that nutrient stimuli in the gastrointestinal (GI) tract, especially in the small intestine, play a major role in the regulation of appetite and energy intake via modulation of GI motility and hormone release. Increasing our knowledge of how protein affects GI motility and hormone release is of increasing relevance in healthy and undernourished older individuals. In addition to the effects of healthy ageing, there is evidence of differences between undernourished and well-nourished older people, which may potentially result from being undernourished and/or contribute to the undernourished state. Urgent investigation is warranted to determine the effects of oral protein intake, so that protein can be incorporated into their diet to assist in sparing muscle mass without reducing their appetite.

The study aims to characterise in older individuals, the effect of undernutrition on energy intake, appetite, antropyloroduodenal motility, plasma concentrations of amino acids, hormones (i.e. CCK, PYY, ghrelin, GLP-1, GIP, glucagon and insulin) and glucose after intraduodenal protein infusion.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 34613 0
Dr Stijn Soenen
Address 34613 0
Adelaide Health & Medical Sciences Building (AHMS), level 5
Cnr North Tce & George St
Adelaide, SA, 5000
Country 34613 0
Phone 34613 0
+61 8 8313 3638
Fax 34613 0
Email 34613 0
Contact person for public queries
Name 17860 0
Dr Dr Stijn Soenen
Address 17860 0
Adelaide Health & Medical Sciences Building (AHMS), level 5
Cnr North Tce & George St
Adelaide, SA, 5000
Country 17860 0
Phone 17860 0
+61 8 8313 3638
Fax 17860 0
+61 8 8313 7794
Email 17860 0
Contact person for scientific queries
Name 8788 0
Dr Dr Stijn Soenen
Address 8788 0
Adelaide Health & Medical Sciences Building (AHMS), level 5
Cnr North Tce & George St
Adelaide, SA, 5000
Country 8788 0
Phone 8788 0
+61 8 8313 3638
Fax 8788 0
+61 8 8313 7794
Email 8788 0

No information has been provided regarding IPD availability
Summary results
No Results